Circuit breaker



Patented Apr. 17, 1945 cmcm'r BREAKER Howard M. Wilcox, Wilkinsburg, Benjamin P. Baker, Turtle Creek, and Herbert J. Webb, Forest Hills, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 19, 1942, Serial No. 435,382

16 Claims.

This invention relates to circuit breakers and has for an object the provision of a circuit breaker operating mechanism having an improved shock-absorbing system for stopping the moving parts with minimum shock.

In connection with circuit breakers embodying high speed operating mechanisms, it is important to provide a reliable means for stopping the moving parts without excessive shock in order to avoid damage to the circuit breaker and its mechanism. This is particularly important in gas blast compressed gas operated circuit breakers due to the nature of the mechanism, and the supporting insulators which are usually composed of porcelain. If the compressed air or gas operating means is to be of simple construction, it is not practical to utilize air dashpots for absorbing shock. Moreover, air dash-' pots require frequent attention and are subject to failure.

An object of the invention is the provision of a highspeed circuit breaker mechanism embodying an improved mechanical shock-absorbing system comprising several resiliently mounted masses which absorb the energy of the moving system without developing high impact forces.

Another object of the invention is the pro- Vision of a compressed gas operated circuit breaker embodying a, shock-absorbing system including resilient bumper means built into the Contact operating piston for absorbing energy at both ends of its travel.

Another object of the invention is the provision of a'compressed air circuit breaker having an improved shock-absorbing system including an lnertia bumper for absorbing some of the kinetic energy of the moving parts, the remaining energy being absorbed by a series of resilient means.

Another object of the invention is the provislon of an improved shock-absorbing means for a circuit breaker, the shock-absorbing means including a resilient member which is deformed by impact and exerts a braking action as the decelerating motion continues.

The scope of the invention is defined in the appended claims. The invention itself, however, both as to structure and mode of operation together with additional objects and advantages thereof will be best understood from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawings, in which:

Figure 1 is a side elevational view of a compressed air circuit breaker embodying the features of the invention;

Fig. 2 is an enlarged view, partly in section, of the contact operating mechanism and the shock-absorbing means; and

Fig. 3 is a fragmentary view, partly in section, showing the control valves of the mechanism.

The features of the present invention are illustrated as applied to a circuit interrupter mechanism similar to that disclosed in the copending application of L. R. Ludwig et 211., Serial No. 431,394, filed February 18, 1942; and assigned to the assignee of the present invention.

Referring to Fig. 1 of the drawings, thereference numeral l l designates a structural frame on which is mounted a plurality of hollow insulators l3, I5 and 11 of vitreous insulating material, only the first two of which are visible in Fig, 1. The insulator i1 is shown in Fig. 3. Secured to the upper end of the insulators l3, l5, and I1 is a casing IQ for housing the operating mechanism more fully shown in Fig. 2. The casing l9 supports a hollow insulator 2| of vitreous insulating material which, in turn, supports a circuit interrupting element 23. Another hollow insulator 25 extends upwardly from the element 23 and has a metallic terminal cap 21 secured on its upper end.

A stationary contact member 29 extends downwardly from the terminal cap 21 into the circuit interrupting element 23 and has a stationary contact 30 of the spring pressed, tulip or multiple-finger type on the lower end thereof. A vertically movable contact member 3! coacts with the stationary contact means 30 and extends downwardly through the element 23 and hollow insulator 2| into the casing IS. The low er end of the contact member 3| is coupled to a compressed air operated piston of the operating mechanism as shown in Fig. 2, and which will be more. fully described hereinafter. The movable contact member 3l'is electrically connected to a terminal 33 by means of resilient connector contact means 35 slidably engageable by the contact member 3|, and by a connector strip 31 of conducting material.

Extinction of arcs drawn by the movable contact member 3| is accomplished by an arc extinguisher of the fluid or air blast type which may be of the form fully disclosed in the copending application of L. R. Ludwig and B. P. Baker, Serial No. 373,856, filed January 9, 1941, and assigned to the assignee of the present invention. Since the present application is not concerned with the arc extinguishing structure, it is believed that the general designation of the arc extinguishing unit 99 which is adapted to be supplied with a blast of arc extinguishing fluid, such as compressed air, will be sufiicient to the purpose at hand.

Fluid, under pressure, in this instance, compressed air for extinguishing the arc and also for the operating means of the interrupter, is

stored in a tank 39 mounted within the frame I I. Compressed air is stored in the tank 39 and automatically maintained at a predetermined pressure by means of a suitable motor driven compressor unit, not shown. Extending from the tank 39 is a pipe 4| which has mounted therein and in communication therewith a blast valve mechanism indicated generally at 43. The blast valve mechanism has a housing which communicates through a short section of pipe 45 with the passage through the interior of the insulator l3. The passage through theinsulator: I3 communicates through a pipe 41 and through the hollow insulator 2| with the chamber of the circuit interrupting element 23. Thus, a blast of air under pressure from the tank 39 is conducted to the arc extinguisher 60 by way of the pipe 4|, blast valve 13, insulator I3, pipe 41, and insulator 2|. The blast valve mechanism 43 is of the same construction as that disclosed in the aforemen tioned copending application of L. R. Ludwig et al., Serial No. 431,394, filed February 18, 1942, and, consequently, only a brief description thereof is given here since reference to the aforementioned application may be had for details of construction. Th blast valve mechanism includes a valve 49 which is biased to closed position by a spring and which is caused to be opened by air pressure upon energization of a solenoid 5i.

The movable contact member 3| is operated to open and to closed circuit position by a .compressed air operating means comprising an operating cylinder 53 having a double-acting operating piston, indicated generally at 55, therein which is coupled to the contact member 3!. The operating cylinder 53 is mounted within the casing I9 and has a lower cylinder head 51 secured thereto by bolts 59, the cylinder head being, in turn, secured to the casing I9 by extensions [H which are bolted to the bottom wall of the casing. The lower portion of the movable contact member 3! slidably extends through the offset portion of the pipe 41 and through an opening provided therefor in the upper head 64 of the cylinder, and'the lower end of the contact member is coupled to the operating piston 55.

The operating cylinder 53 has a projection 63 formed integral therewith adjacent the upper end, and this projection has an inlet air passage 65 leading to the upper end of the interior of the operating cylinder. The projection 63 also has a port (not shown) communicating with the passage 35, and this port is connected by a pipe 61 (Fig. 1) to the passage of the hollow insulator I':'. The passage of the hollow insulator I1 is, in turn, connected by a pipe 39 (Fig. 3) to an opening valve mechanism H for controllingthe flow of compresser air to efiect an opening operation of the circuit breaker.

The lower end of the operating cylinder 53 is also provided with an integral projection 13 having an air passage 15 therein communicating with the lower end of the operating cylinder, and this projection has a port (not shown) which communicates with a pipe I! (Fig. 1). The other end of the pipe 'I'! communicates with the passage through the supporting insulator I5 to the lower end of which is connected a pipe 79 leading to a closing valve mechanism, indicated generally at 8!.

Compressed air for operating the piston 55 to effect opening and closing of the circuit interrupter is derived from the air storage tank 39. For this purpose, the pipe Al is provided with two branch pipes 83 and 95 (Fig. 3). The pipe 83 is connected to the opening valve mechanism II, whereas the branch pipe 85 is connected to the closing valve mechanism 8|. Compressed air from the opening valve II is conducted through the pipe 69 and passage of insulator I7 and pipe 61 tothe upper end of the operating cylinder. Closing valvemechanism 8! controls the flow of compressed air through the pipe '19, passage through insulator I5 and pipe (1 to the lower end of the operating cylinder 53 to effect closing operation of the circuit interrupter.

In order to obtain high speed opening and high speed reclosing operation of the breaker, it is necessary to dump the air in the cylinder ahead of the direction of movement of the operating piston to atmosphere so as to prevent, air ahead of the piston from retarding the movement thereof. Two dump valves 81 and 89 are provided for this purpose. The dump valve 89 is mounted in a projection 9| formed integral with the cylinder adjacent its upper end. This projection has a passage 93 leading to the upper portion of the operating cylinder and also has an atmosphere exhaust port 95 which is normally closed by the valve 89. The valve 89 has a rod 91 connected thereto, the lower end of which engages a dump valve operating piston 99 that is movable in a cylinder provided in the projection 13, The dump valve 89 is biased closed by a spring I9! and is adapted to be operated to open position by the valve piston 99 immediately upon the flow of compressed air to the lower side of the breaker operating piston 55. Opening of the valve 89 opens the upper end of the operating cylinder 53 to atmosphere through the port 95, so that air above the breaker operating piston 55 will be at a low pressure, and hence will not retard closing movement of the piston.

The other dump, valve 81 is mounted in a proiection H13 formed integral with the cylinder 53 adjacent the lower end thereof; The projection I93 has a passage I05 therein which communicates with the lower portion of the breaker operating cylinder 53, and also has an exhaust port I96 leading to atmosphere. The dump valve 81 has an operating rod I01 connected thereto, the upper end of which engages the valve operating piston I09 movably mounted in a cylinder of the projection 93. The dump valve 81 is biased closed by a spring Ill and is adapted to be opened by I the valve piston I09 immediately upon the flow of compressed air to the upper end of the breaker operating cylinder 53. Opening of the dump valve 81 connects the lower portion of thebreaker operating cylinder 53 to atmosphere through the exhaust port I99, thereby causing air'below the breaker operating piston 55 to be at a low pressure so that it will not retard the opening move ment of the operating piston. I

The opening valve mechanism H and the closing valve mechanism 8! are of the same construction as disclosed in the aforementioned copending application of L. R. Ludwig et al., SerialNo. 431,394, and only a brief description thereof will be 'give'n'in this application as the details of construction of the valve mechanisms are not necessary for a complete understanding of the present invention. Referring to Fig. 3, the opening valve mechanism II has a valve H3 which is biased closed and which is caused to be opened by a valve piston operated by air pressure in the pipe 83 'upon energization of a solenoid II5.

compressed air from the pipe 85 upon energization of a solenoid I I9. The valve mechanisms II and 8| are pneumatically interlocked by means of apipe I2I, as disclosed in the aforementioned copending application of L. R. Ludwig et al., Serial No. 431,394, so that an opening impulse will always take precedence over a closing impulse.

The control circuits for controlling the solenoid of the blast valve mechanism 49 and the solenoids H5 and II 9 of the opening and closin valves may be substantially the same as disclosed in the aforementioned copending application of L. R. Ludwig et al., Serial No. 431,394, and are not shown in this application as the details thereof are unnecessary for an understanding of the present invention. It is believed sufficient to state that the solenoid 5I of the blast valve mecha manual closing control switch or by a suitable reclosing relay. As soon as the closing operation is completed, the closed relay is deenergized. whereupon the closing valve BI is returned to closed position.

In accordance with the present invention, the mechanism is provided with an improved mechanical. shock-absorbing system comprising a series of elements, masses and resilient means arranged to absorb the kinetic energy of the moving parts without developing high impact forces. Referring to Fig. 2, the shock-absorbing system includes a pair of annular metal bumpers I25and i2! which are resiliently supported in the opposite ends of the operating cylinder 53 in positions to be engaged by the operating piston as it ap proaches each end of its stroke. The bumpers I25 and I2! are mounted for limited vertical movement in the slightly enlarged bore portions which are provided in each end of the operating cylinder 53, and the outer diameter of the bumpers I25 and I21 is only slightly less than that of the enlarged bore portions.

Resilient means comprising a plurality of annular rings I29 of resilient or elastic material are "disposed in back of each of the bumpers I25and I21 for the purpose of absorbing some of the energy. Downward movement of the upper bumper I21 is limited by the shoulder formed by the upper enlarged bore portion adjacent the upper end of the cylinder, and the resilient'rings I29 forthis bumper are disposed between the bumper and the head 64 of the cylinder. 'Upward movement of the lower bumper I25 is limited by the shoulder formed by the lower enlarged bore portion adjacent the lower end of the cylinder, and the resilient rings I29 for this lower bumper I25 bear against the underside of the bumper, a metal ring I3I being provided beneath the lowermost ring I29. The outer diameter of the resilient rings I29 and the metal ring I3I is only slightly less than the diameter of the enlarged bore portion so that these rings have a relatively close fit in the bore. The lower metal bumper I25 and its resilient rings I29 are supported on the enlarged head I33 of a movable inertia mass I35 which is mounted for limited vertical movement in a bore of the lower cylinder head 51. This inertia mass is, in tm-n, sup ported by a. relatively heavy helical compression spring I3! disposed in the bore of the lower cylinder head 51. The upper end of the spring I3? bears against the enlarged head of the inertia mass and the lower end of the spring bears against a closure cap I 39 which is secured to the lower end of the cylinder head 51 by a plurality of screws MI. The spring I31 biases the inertia mass and the bumper assembly to its upper limiting position, as shown in Fig. 2. In this position the lower end of the inertia mass is disposed in slightly spaced relation to a cylindrical bumper stop I43 which is composed of resilient material, such as rubber. The bumper stop I43 is mounted within a-well provided therefor in the closure cap I39.

The breaker operating piston has a resilient shock-absorbing means comprising a spring built therein which acts to absorb some of the kinetic energy of the moving parts at each end of the stroke of the piston. The operating piston 55 comprises an outer metal shell M5 through which the lower portion of the contact member 5.! extends. The upper end of the piston shell I45 has an inwardly extending integral flange portion HIT, and a ring or bushing I49 is threaded into the lower end of the shell I45. A pair of flanged metal rings I5I and I53 are movably mounted within the shell I45 adjacent the opposite ends thereof, the outer necks of these rings being slidably received in the flange I4! and bushing I49, respectively. A helical shock-absorbing compression spring I55 is mounted within the shell I 45 and is disposed between the flange portions of the movable rings I5I and I53. The contact member M has a reduced portion 15] which extends downwardly through the rings I 5I and I53, and the shoulder provided by this reduced portion of the contact member bears against and abuts the upper end of the movable ring I5 I. A look nut I59 is threaded on the lower end of the reduced portion of the contact member 3|, and this nut bears against and abuts the lower edge of the lower movable ring I53, as shown in Fig. 2. It will thus be seen that the piston shell I45 is resiliently coupled to the contact member 3|. The upper end of the movable inertia mass I35 is provided with a recess IIiI to accommodate the projecting lower threaded end of the movable contact member 3I,

The resilient rings I29 which are associated with the metal bumpers I25 and I2! are composed of a resilient or elastic material which suflers deformation with very little volumetric compression upon impact or compression of the rings, one suitable material being rubber, for example. Upon impact, the resilient rings III!) are defonrned and the sides thereof expanded and pressed tightly against the bore of the cylinder so as to exert a frictional braking action against the bore of the cylinder as they are moved along with the piston. This braking action decelerates the piston 55 and moving parts, and upon release of the driving force, the braking action is automatically removed, and the rings returned to their original shape. I

The operation of the circuit interrupter is briefly as follows: Assuming the circuit breaker to be in theopen position as illustrated in Figs. 1 and 2, closing operation of the circuit breaker is caused to take place upon energization of the closing valve solenoid H9. Opening of the closing valve 8! causes the flow of compressed air from the storage tank 39 through the branch pipe 85, closing valve 8 I, hollow insulator l5, and pipe I? to the lower side of the breaker operating piston 55. The flow of compressed air immediately causes opening of the dump valve 89 and effects movement of the operating piston 55 upwardly to its upper end position, thereby closing the circuit breaker.

An opening operation of the circuit breaker isproduced upon energization of the opening valve solenoid H5. Opening of the valve II causes the flow of compressed air from the storage tank 39 through the branch pipe 83, opening valve II, hollow insulator I1, and pipe 6! to the upper side of the breaker operating piston 55. This flow of compressed air immediately causes opening of the dump valve 81, thereby opening the lower end of the cylinder to atmosphere, and the compressed air acting on the top of the operating piston 55 moves the same downwardly to its lowermost or open position, thereby efiecting opening of the circuit-breaker. Since the blast valve controlling electromagnet is energized simultaneously with the opening valve solenoid H5, a blast of compressed air is directed to the circuit interrupting element 23 to quickly extinguish the arc drawn by the movable contact member SI during the initial portion of the opening operation.

During the latter portion of the downward or opening movement of the operating piston 55, the shell M5 thereof strikes the lower metal bumper I25. The impact compresses the shockabsorbing spring I55 and also compresses and deforms the resilient rings I29, thereby absorbing some of the kinetic energy. The metal bumper I25, rings I29, and the relatively heavy inertia mass I35 are thereby accelerated and moved downwardly by the piston to compress the relatively heavy spring I3'I,.thereby absorbing additional amounts of kinetic energy. The compression of the resilient rings I29 causes the sides thereof to be expanded and pressed tightly against the enlarged bore portion of the cylinder, thereby exerting a considerable frictional braking action as these rings are moved along with the piston. Thi action absorbs some more of the kinetic energy of the moving parts. The lower end of the inertia mass finally strikes the resilient bumper stop I43, compressing the same and bringing the parts to a stop as the remaining portion of the energy is absorbed. After the motion of'the piston has been brought to a stop, the spring I3? and the resilient rings I29 expand and return the parts to the normal position, as shown in Fig. 2.

During the final portion of the closing operation, the kinetic energy is absorbed by the piston 55 striking the upper bumper plate I21 and compressing the upper. resilient rings I29 and the shock-absorbing spring I55 of the piston itself. The closing speed of the piston is not as high as the opening speed, and the tulip type stationary contacts 30 absorb some of the kinetic energy during the final portion of the closing operation.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given the broadest reasonable interpretation permissible in the light of the prior art.

We claim as our invention:

1. In a circuit breaker, movable contact means, high speed operating means therefor including a movable member connected to said contact means, shock-absorbing means comprising a metal bumper movably mounted in a guide, resilient means of deformable material in back of said bumper, said resilient means being deformed by impact and thereby pressed tightly against said guide to exert a braking action for decelerating said movable member, a movable inertia mass supporting said resilient means and bumper, and spring means supporting said inertia mass. g

2. In a high speed circuit breaker operating mechanism, a cylinder, a fluid operated piston in said cylinder for actuating the breaker, shockabsorbing means comprising a metal bumper slidably supported in one end of said cylinder, resilient means of deformable material in back of said bumper, said resilient means being deformed by impact and the sides thereof thereby pressed tightly against the wall of said cylinder to exert a braking action for decelerating said piston, a movable inertia mass supporting said resilient means and bumper and spring means supporting said. inertia mass.

3. In a circuit breaker, movable contact means, high speed operating means therefor including a member connected to said contact means, shockabsorbing means comprising a resilient shock absorber carried by said member and efiective to absorb some of the kinetic energy at each end of the stroke, a metal bumper movably supported in a guide and disposed to be engaged by said resilient shock absorber, a movable inertia mass supporting said metal bumper, and resilient means supporting said inertia mass.

4. In a circuit breaker, movable contact means, high speed operating means therefor including a movable member connected to said contact means, shock-absorbing means comprising a resilient shock absorber carried by said movable member and effective at each end of the stroke to absorb some of the kinetic energy, a metal bumper movably supported in a guide and disposed to be engaged by said resilient shock absorber, resilient means of deformable material in back of said bumper, said resilient deformable means being deformed by impact and its sides thereby pressed tightly against said guide to exert a braking action for decelerating said movable member, a movable inertia mass supporting saidresilient deformable means and said bumper, and spring means supporting said inertia mass.

5. In a circuit breaker having relatively movable contacts, high speed operating means therefor comprising a cylinder, a contact actuating rod slidably extending into said cylinder through one end, a fluid pressure operated piston in said cylinder coupled to said rod for actuating the breaker, and means including a single spring means mounted on said piston and absorbing energy. at both ends of the travel of said piston.

6. In a circuit breaker having relatively movable contacts, high speed operating means therefor comprising a cylinder, a breaker actuating rod slidably extending into said'cylinder through one end thereof, a fluid pressure operated piston in said cylinder coupled to said rod for operating the breaker, a shock-absorbing bumper adjacent each end of said cylinder in a position to be engaged by said piston, and one resilient means mounted on said piston and absorbing energy at both ends of the travel of said piston.

'7. In a high speed circuit breaker operating mechanism, a cylinder, a breaker actuating rod slidably extending into said cylinder through one end, a fluid pressure operated piston in said cylinder coupled to said rod for operating the breaker, shock-absorbing means including resilient means adjacent each end of said cylinder and a spring means carried by said piston and absorbing energy at both ends of the travel of said piston.

8. In a high speed circuit interrupter operating mechanism, a cylinder, an interrupter actuating rod slidably extending into said cylinder through one end thereof, a fluid pressure operated piston in said cylinder coupled to said rod for operating the interrupter, a movable inertia mass mounted in said cylinder adjacent one end, means for resiliently opposing movement of said mass, and spring means carried by said piston and through which the energy of said actuating rod is transmitted to said inertia mass for absorbing energy at one end of the travel of said piston.

9. In a high speed circuit interrupter operating mechanism, a cylinder, an interrupter actuating rod slidably extending into said cylinder through one end thereof, a fluid pressure operated piston in said cylinder coupled to said rod for operating the interrupter, shock-absorbing means comprising a metal bumper movably mounted adjacent each end of said cylinder, resilient means of deformable material in back of each bumper, and spring means through which said actuating rod is coupled to said piston for absorbing energy at both ends of the travel of said piston upon engagement with said bumpers.

10. A high speed circuit breaker opera-ting mechanism comprising a cylinder, a breaker actuating rod slidably extending into said cylinder through one end, a fluid operated piston in said cylinder coupled to said rod for operating the breaker, said piston comprising a shell through which said breaker actuating rod extends, a pair of rings movably mounted in said shell, and a spring disposed in said shell between said rings, said rod having portions on opposite sides of said piston abutting said rings.

11. A high speed circuit breaker operating mechanism comprising a cylinder, a contact actuating rod slidably extending into said cylinder through one end thereof, a fluid operated piston in said cylinder coupled to said rod for operating the breaker, said piston comprising a shell through which said rod extends, a pair of rings movably mounted in said shell one adjacent each end, said shell having end portions to limit outward movement of said rings, a compression spring disposed in said shell between said rings, said rod having a shoulder portion at one end of said piston for abutting one of said rings and having removable means on the other side of the piston for abutting the other ring, and resiliently mounted bumper means adjacent at least one end of said cylinder adapted to be engaged by one end portion of said piston.

12. In a circuit breaker having relatively movable contacts, high speed operating means therefor comprising a cylinder, a contact actu-v ating rod slidably extending into said cylinderthrough one end, a fluid pressure operated piston in said cylinder, resilient means by which said piston is coupled to said rod for actuating the breaker, and said resilient means being mounted in said piston between. the opposite end surfaces of the piston and absorbing kinetic energy at both ends of the travel stroke of said piston.

13. In a high speed circuit breaker operating mechanism, a cylinder, a fluid operated piston in the cylinder for actuating the breaker, and shock-absorbing means including resilient means disposed at least at one end of the cylinder and a biased inertia member backing up said resilient means to help decelerate the piston when it engages the resilient means at the end of its stroke.

14. In a high speed circuit breaker, movable contact means, a cylinder, 2. fluid operated piston reciprocal in the cylinder and mechanically con nected through resilient means to the contact means to cause the operation thereof, and a heavy movable inertia. means disposed at one end of the cylinder and biased against movement under impact from the piston to assist in decelerating the piston.

15. In a circuit breaker having relatively movable contacts, high speed operating means therefor comprising a, cylinder, a contact actuating rod slidably extending into said cylinder through one end, a fluid pressure operated piston in said cylinder coupled to said rod for actuating the breaker, a weight member to which the energy of said piston is transmitted by impact, a spring for absorbing energy from said weight member and means of resilient deformable material for finally stopping the travel of the weight member and the piston.

16. In a circuit breaker having relatively movable contacts, operating means therefor comprising a cylinder, a contact actuating rod slidably extending into said cylinder, a fluid pressure operated piston in said cylinder, stop means at each end of said cylinder engageable by said piston, and resilient means coupling said piston to said contact actuating rod and reducing the shock when the piston engages each of the stop means.

HOWARD M. WILCOX. BENJAMIN P. BAKER. HERBERT J. WEBB. 

